Hydrodesulfurization and hydrodenitrogenation

Tungsten alloyed with nickel, cobalt, or rhodium in thin layers on alumina supports, also sulfided, is used on an industrial scale as a catalyst in crude oil processing (hydrotreating, hydrocracking, reforming, hydrodesulfurization, and hydrodenitrogenation), as well as in Fischer-Tropsch synthesis (alcohol formation from CO + H2). 

As catalyst, besides others, tungsten is used as nickel alloy in thin layers on alumina supports. During the reaction, tungsten is converted, at least at the surface, to WS2, which also acts as a catalyst. 

The HDS and HDN reactions occur during hydrotreating and hydroreforming of crude oil, and the catalyst also promotes hydrogenation of unsaturated hydrocarbons and hydrodeoxygenation. 

There are several reasons for the reduction of sulfur and nitrogen concentrations in petroleum feedstocks  

The necessity to improve HDS and HDN has recently boosted R D efforts. The search for better catalysts has also improved our understanding of the complicated processes which occur at the catalyst surfaces. 

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The primary determinant of catalyst surface area is the support surface area, except in the case of certain catalysts where extremely fine dispersions of active material are obtained. As a rule, catalysts intended for catalytic conversions utilizing hydrogen, eg, hydrogenation, hydrodesulfurization, and hydrodenitrogenation, can utilize high surface area supports, whereas those intended for selective oxidation, eg, olefin epoxidation, require low surface area supports to avoid troublesome side reactions. 

Reactions occurring in hydrotreatment units are mainly hydrodesulfurization and hydrodenitrogenation of sulfur and nitrogen compounds. In... 

T. Kabe, A. Ishiara, W. Qian (Eds.), Hydrodesulfurization and Hydrodenitrogenation, Wiley-VCH, Weinheim, 1999. 

In general, it can be concluded, that although a large scale biphasic solution process for hydrodesulfurization and hydrodenitrogenation is not likely to come soon, there are promising results in homogeneous catalysis which can lead to constmction of such processes in the future. 

Trickle-bed reactors usually consist of a fixed bed of catalyst particles, contacted by a gas liquid two-phase flow, with co-current downflow as the most common mode of operation. Such reactors are particularly important in the petroleum industry, where they are used primarily for hydrocracking, hydrodesulfurization, and hydrodenitrogenation other commercial applications are found in the petrochemical industry, involving mainly hydrogenation and oxidation of organic compounds. Two important quantities used to characterize a trickle-bed reactor are... 

Perylene, with tetrapalladium sandwich complex, 8, 345 PES, see Photoelectron spectroscopy PE spectroscopy, see Photoelectron spectroscopy Petroleum, and hydrodesulfurization and hydrodenitrogenation, 1, 760 (—)-PF1163B, via ring-closing metathesis, 11, 243 PFSs, see Polyferrocenylsilanes pH, role in aqueous media, 1, 828 Pharmaceuticals... 

Table 5-5 Typical Composition of Hydrodesulfurization and Hydrodenitrogenation Catalysts...

A Comparison of the Hydrodesulfurization and Hydrodenitrogenation Activities of Monolith Alumina Impregnated with Cobalt and Molybdenum and a Commercial Catalyst... 

R. A. Sanchez-Delgado, Organometallic Modeling of the Hydrodesulfurization and Hydrodenitrogenation Reactions , Kluwer Academic Publishers, Dordrecht, 2000. 

On the other hand, zeolite-based catalysts have not developed any significant interest in other important processes such as catalytic reforming, hydrogenation of olefins and aromatics, hydrodesulfurization and hydrodenitrogenation. This lack of utility is attributable, in part, to the high cracking activity exhibited by active zeolite-based catalysts. 

D.S. Soni and B.L. Crynes, A comparison of the hydrodesulfurization and hydrodenitrogenation activities of monolith alumina impregnated with cobalt and molybdenum and a commercial catalyst, ACS Sympos. Ser. 756 207 (1981). 

Mochida, I. and Choi, K.H. An overview of hydrodesulfurization and hydrodenitrogenation. Journal of the Japan Petroleum Institute, 2004, 47, 145. 

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